Graham J K
Department of Physiology, Colorado State University, Fort Collins, USA.
Vet Clin North Am Equine Pract. 1996 Apr;12(1):131-47. doi: 10.1016/s0749-0739(17)30300-0.
The main advantage to using frozen semen in any breeding program is faster genetic gain for the inherited trait desired. Milk production of dairy cows doubled (from 26,000 to 52,000 kg of milk/cow per year) between 1950 and 1980, because the dairy industry was using semen only from bulls with the greatest genetic potential for milk production. This genetic gain could have been achieved without the use of frozen semen; however, the time required to achieve that same genetic progress would have been lengthened exceedingly. Fertility rates using frozen stallion spermatozoa are not equal to that of fresh semen, but with careful management of both the stallion and the mare fertility rates of 40% to 60% can be achieved for a single mare reproductive cycle and fertility rates of 60% to 75% during the course of a breeding season can be expected for a number of stallions. Because pregnancy rates have increased and because many breed registries now condone the use of frozen stallion semen, more people in the equine industry are using frozen semen. It has been the attempt of this article to make the practitioner aware of some of the problems that can occur when processing, freezing, storing, and using frozen semen, and how to control those problems. The practitioner also should be aware that there is large variation in semen quality from stallions, and that spermatozoa from some of the problem stallions can be improved by altering a "standard protocol," but that semen from some stallions will not cryopreserve effectively, regardless of the efforts put forth.
在任何育种计划中使用冷冻精液的主要优势在于，对于所需的遗传性状能更快地实现遗传进展。1950年至1980年间，奶牛的产奶量翻了一番（从每年每头奶牛产奶26,000千克增至52,000千克），这是因为乳制品行业仅使用具有最大产奶遗传潜力的公牛的精液。不使用冷冻精液也能实现这种遗传进展；然而，实现相同遗传进展所需的时间将会大幅延长。使用冷冻种马精子的受孕率不及新鲜精液，但通过对种马和母马的精心管理，单个母马繁殖周期的受孕率可达40%至60%，在繁殖季节中，一些种马的受孕率有望达到60%至75%。由于受孕率有所提高，且许多品种登记机构现在认可使用冷冻种马精液，马匹行业中有更多人开始使用冷冻精液。本文旨在让从业者了解在处理、冷冻、储存和使用冷冻精液时可能出现的一些问题，以及如何控制这些问题。从业者还应意识到，不同种马的精液质量差异很大，一些有问题种马的精子可以通过改变“标准方案”得到改善，但无论付出多大努力，一些种马的精液都无法有效冷冻保存。
